Composite-joint construction



UNITED STATES ROBERT S. BLAIR, OF SOUND BEACH, CONNECTICUT.

COMPOSITE-JOINT CONSTRUCTION.

Specification or' Letters Patent.

Patented Oct. 18, 1921.

Application led. December 23, 1915. Serial No. 68,339.

To @ZZ wwm t may concern Be it known that I, ROBERT S. BLAIR, a citizenof the United States, and resident of Sound Beach, in the county ofFairfield and State of Connecticut, have invented certain new and usefulImprovements in Composite- Joint Construction, of which the following isa specication.

This invention relates to jointvconstruction. One of the objects thereofis to provide a strong, rigid, practical joint which shall be durableunder varying conditions of use. Another object is to provide jointconstruction of the above type in which the parts are readily assembledor taken apart. Another object is to provide a practical and convenientart for making a joint of the above type. Other objects will be obviousor pointed out'hereinafter.

The invention accordingly consists in the features of construction,combinations of elements and arrangement of parts and in the severalsteps and relation and order of such steps, all of which will beexemplified in the matter hereinafter described and the scope of theapplication of which will be indicated in the following claims.

In the accompanying drawing in which is shown one of the variouspossible embodiments of the mechanical features of the invention- Figurel is a side elevation of a member having a tenon formed thereon.

Fig. 2 is a longitudinal section through a portion of a member having amortise adapted to receive a tenon of the above form.

Fig. 3 is a similar section taken through a completed joint,substantially along theine B-B of Fig. 5. Y

Fig. 4 is a similar view taken through the same joint along theline C-Cof Fig. 5.

Fig. 5 is a sectional view taken along the line A-A of Fig. 3.

Fig. 6 is a sectional view on a smaller scale showing one of the stepsin the art of forming a joint of this nature.

Similar reference characters 'refer to similarparts throughout theseveral views of the drawing.

Referring now to Fig. 1 of the drawing there is shown a member 1provided with a tenon 2, this member being preferably of wood, and itmay here be noted that the term wood is used in a broad sense to denoteany organic, fibrous material. The tenon 2 is provided with the grooves3, 4 and 5 with grooves 8, 9, and 10, although each of which extendsentirely about the tenon, that is it traverses its entire circumferencein a plane transverse thereof. These grooves are preferably shaped asshown with a more abrupt lower face 7. The grooves moreover increase indepth and width toward the lower end of the tenon, that is, the groove 4is larger than the groove 3 and the groove 5 larger than the groove 4,in the preferred embodiment of this invention. The various groves areconnected with one another by the longitudinal grooves 8 and groove 5 isconnected by the longitudinal groove 9 with the end of the tenon. Inlike Vmanner the groove 3 is connected by a the memgroove 10 with theshoulder 11 on ber l.

It is to be understood that the longitudinal grooves 8, 9, and 10 arepreferably duplicated on each face of the tenon as indicated by thedotted lines 12.

In Fig. 2 of the drawing is shown the remaining member 13 of the joint.This member is provided'with a mortise 14 and it is to be understoodthat the terms mortise and tenon areused in their usual broad sense. Thewalls of the mortise 14 are preferably provided with grooves l5, 16, and17 which are so positioned as to register respectively with'the grooves3, 4, and 5 and are similar in size and shape except that each of thesemortise grooves has its most abruptly inclined face 18 at the upper sideand its less inclined face 19 beneath or toward the bottom of themortise. The walls of the niortise are also preferably provided withlongitudinal grooves 2O registering these are not essential, if thegrooves of the tenon are properly formed and disposed. There '1sprovided at the bottom or end wall of the mortise 14 a transverse groove21 which leads to a recess 22 each of the side walls of vwhich areundercut.

t may also be noted that there is provided at the lower end of the tenon2 an undercut recess 28 positioned` to register with the recess 22 whenthe parts are assembled.

The following method is preferably employedin assembling the joint. Themem- Vbers are preferably first heated up to a pointv just below theirscorching point and it may be noted by the latter term is meant thattemperature at which the surface of the wood is softened or otherwiseinjured by heat.

Of course in this heating of the wood care should be taken that theexterior surface of the parts are not heated to such an extent as toinjure their finish. With the members thus heated there is poured intothe mortise in melted condition a metallic alloy. This alloy should beof such nature as to flow readily and completely at a point below thescorching point of the wood and, for example, a suitable alloy may bemade of cadmium l part, tin 1 part and bismuth 2 parts. This alloy isnot only melted but is preferably raised to a temperature materiallyabove its melting point and then a small quantity introduced into theheated mortise'14.

The quantity of the material thus introduced is not more than a fractionof the total depth of the inortise, and depends on the volume of thespaces which are to be filled thereby, as hereinafter described, in thecoinpleted joint.

As the tenon is forced downwardly into this molten metal, the latter isdisplaced upwardly and fiows readily through the several grooves 8, 9and 10 and the registering parts in the mortise 14 until the tenon isforced home. The metal fills all of the recesses between the grooves 3,4 and 5 and the registering grooves in the mortise, and also fills thespaces 22 and 23. The excess of metal, if there be any, may pass offbetween tlie shoulder 11 and the opposite portion of the member 13 andthe parts are preferably so formed as to provide a slight crevice 24within which a film of metal may be formed. This crevice may be made byslightly undercutting the shoulder.

In the above vaction it is to be noted that the heating of the woodbefore the metal is brought in contact therewith tends to cause themetal to enter into the minute pores of the wood and thus impregnate theportion of the wood adjacent the metal and better adapt it to withstandpressure. To achieve the latter results properly the metal should besuperheated, that is heated above its meltino` point, so that it willstill remain fluid if it be slightly cooled as it ends to enter into thepores of the wood.

In the above process the metal is forced into every minute crevicebetween the surface of the tenon and the opposite surface of themortise, and an eiiicient joint is thus assured. It may here be notedthat the term forced as used herein in connection with the fluid metalis employed in a broad sense to denote the application of a positiveforce and distinguish from the ordinary action of gravity, and it mayalso be noted that this force may be attained in other ways than bydisplacing the metal, as the latter may be forcibly injected in fluidform through a suitable small opening with a vent, or even atmosphericpressure may be utilized by suction of the air from the interstices between the tenon and mortise with the parts in assembled condition. Thereare however certain advantages inherent in the method first abovedescribed, although certain broad features of this invention may beotherwise carried on as herein indicated. l

After the joint is permitted to cool it takes the form indicated inFigs. 3, 4 and 5 of the drawings.

Fig. 4 which is taken through the longitudinal passages 8, 9 and l0shows clearly the metal at 25 resting within the undercut recesses 22and 23 thus Arigidly anchoring the tenon at its end. The varioustransverse or circumferential grooves in the mortise and tenon providethe -rings of metal 26, 27 and 28 which extend entirely about the tenonas indicated in F igs. 3 and 5 and which together with the longitudinalgrooves form a grid of metal on each of thewalls of the tenon, securelyinterlocking it with the entire walls of the mortise. The rings 26, 27and 28 increase in cross section in the above order and thus interlockto an increasing dcgree with the parts against which they rest, thisarrangement giving a maximum interlocking with a minimum weakening ofthe tenon at the point at which it is exposed to the greatest bendingystress. Also the inclination of the walls of the various circumferentialgrooves is most abrupt in the direction in which it is called on toresist pressure. For example, in the metal ring 2S, the walls 29 and 30are those which are exposed to pressure whenever there is any tendencyfor the tenon to be pulled out of the mortise. The metal in the crevice23 provides a rigid bearing between the parts at this point wheneverthere is any tendency of the member l to rock with respect to the member13. It is to be undestood that by the term scorching point .is meantsuch teinperature as will 'substantially affect the surface of woodwithin the time required for the metal to cool. Y

There is thus provided a joint which is extremely rigid and issubstantially unaffected by moisture. Also, no auxiliary devices such asnails or screws are required to complete the joint. n

If it is desired to take the members apart it is necessary only to heatthe wood to such a temperature as will melt the metal whereupon thetenon is readily removed from the mortise, and the metal may be savedfor the reassembling of the joint. It may also be noted at this pointthat in certain fusibleV alloys like the above the inetal uponsolidiicati'on expands instead of contracts and thus fits more tightly.

As various changes may be made in the above construction and as theabove described art may be carried on in other ways it is to beunderstood rthat all matter herein lli described and all matter shown inthe accompanying drawing is to be interpreted as illustrative and not ina limiting sense.

Having described this invention, I claim- 1. In joint construction, lincombination a member provided with a tenon, a member provided with amortise, in which said tenon lies, one of said members being wooden, anda member interlocking with said tenon and the walls of said mortise andformed of a metallic alloy fusible at a temperature below the scorchingpoint of the wood.

2. In joint construction, in combination a wooden member provided with atenon, a wooden member provided with a mortise in which said tenon liesand a member extending between said tenon and the walls of said mortiseand interlocking with the surfaces of both of the same, said lattermember being formed of a metallic alloy fusible at a temperature belowthe scorching point of the Wood.

3. In joint construction, in combination a wooden member provided with atenon, a wooden member provided with a mortise in which said tenon liesand a member extending between the tenon and the walls of said mortiseinterlocking with the surfaces of both of the same, said latter memberbeing formed of a metallic alloy constituted to tend to expand uponsolidication.

4. In joint construction, in combination, a wooden member provided witha tenon, a wooden member provided with a mortise in which said tenonlies and a member extending between the tenon and the walls of saidmortise interlocking with the surfaces of both of the same, said lastmember being formed of a metal fusible at a low temperature and shapedto' enter and interlock with the pores of the wood.

5. In joint construction, in combination a wooden member provided with atenon, a wooden member provided with a mortise in which said tenon liesand a metal member fusible at a low temperature and extending betweensaid tenon and said mortise, said member being shaped to enter the poresof the wood with which it contacts.

6. In joint construction, in combination, a wooden member having amortise formed therein, a second wooden member having a tenon restingwithin said mortise, said parts being so formed as to provide a passageextending from the lower to the upper portion of said mortise with saidtenon positioned therein, and a retaining member formed of a metallicalloy fusible through wood interposed between said tenon and the wallsof said mortise.

7. In joint construction, in combination, a pair of wooden members inone of which is a recess and the other of which fits in said recess,substantially registering grooves formed in the walls of said recess,and in the outer surface of the member therein and holding means formedof an alloy fusible through wood resting within said registeringvgrooves and locking said members in an assembled relation.

8. In joint construction, in combination, a pair of members, one ofwhich is recessed a-nd the other of which fits within said recess, oneof said members being provided with a transverse groove opposite whichthe other member rests, said groove being formed to provide a moreabrupt surface in one direction than in the other, and holding meansformed of an alloy fusible at a low temerature cast within said grooveand tending to hold said members together.

9. In oint construction, in combination, a pair of members one 'of whichis recessed and the other of which fits within said recess, groovesextending about the walls of said recess transverse to its depth andeach having a more abrupt surface in the direction toward the open endof the said recess than in the reverse direction, said second memberbeing provided with grooves substantially registered with said firstgrooves with the parts in assembled relation, said last each having asurface toward the bottom of the recess; more abrupt than that towardthe top, and holding means formed of a metallic alloy fusible at a lowtemperature cast within said grooves.

10. In joint construction, in combination, a member provided with arecess, a second member fitted within said recess, said rst memberhaving a series of grooves extending about the walls of said recess andsaid second member having a series of substantially registering groovesand holding means formed of a metallic alloy fusible at low temperaturefitted within said grooves, said several grooves being of increasingdepth in a direction toward the bottom of said recess.

l1. In joint construction, in combination a member provided with arecess, a second member fitting said recess, a series of groovesextending about the surface of one of said members at a point oppositethe surface of the other of said members within said recess and holdingmeans formed of a metal fusible through wood cast within said grooves,said grooves being shaped to comprise portions extending toward the openend of the recesses whereby said metal may flow toward said end.

12. In joint construction, in combination, a wooden member providedwithxa mortise, a wooden member provided with a tenon, a series ofsubstantially registering grooves formed in the outer surface of saidtenon and the walls of said mortise and extending about said mortisewhereby there is provided a series of circumferential passages aboutsaid tenon and entering into said tenon and the walls of said mortiseand holding means formed of an alloy fusible through wood cast withinsaid passage.

13. In joint construction, in combination, a pair of wooden membersforming a mortise and tenon and holding means formed of an alloy fusiblethrough wood, interposed between said tenon and mortise and providedwith outer inclined surfaces upon opposite sides of said tenoninterlocking with the walls of said mortise.

14;. In joint construction, in combination, a wooden member providedwith a mortise, a wooden member provlded with a tenon Vresting withinsaid mortise, and a shoulder awooden member provided with a tenon.fitting within said mortise, and a member formed of an alloy fusiblethrough wood, entering into the end of said tenon and the bottom wall ofsaid mortise.

16. In joint construction, in combination, a pair of wooden members, oneof which has a mortise formed therein, and the other of which has atenon fitting within said mortise, and a member formed of an alloyfusible through wood and shaped to lock together said mortise and tenon.

17. The art which comprises forming a mortise with undercut walls in awooden -member, forming Ia tenon upon a second wooden member7 heatingsaid mortise and tenon, placing a molten metallic alloy fusible at lowtemperature within said mortise,

